This invention relates to an improved device for direct-flow treatment of fiber-containing material, e.g., textiles, fleeces or paper by a gaseous or liquid treatment agent circulated in the device, with a transport member comprising a fluid permeable drum having non-permeable bases on its ends and being under suction draft, said transport member being covered on its periphery with a screen-like covering, sheet metal strips extending rectilinearly and unbent from base to base between the bases of the drum, the widths of said strips extending in a radial direction, one-piece connector members which are uniformly disposed between the sheet metal strips over the length of the drum, and which are formed of a width corresponding to the required spacing of immediately adjacent sheet metal strips, the connector members being securely connected at both ends with adjacent sheet metal strips, and respective connector members being web-shaped and provided in the peripheral direction of the drum, with at least one bore for at least one screw and/or similar attachment element provided with a thread, and connected to the two adjacent sheet metal strips or connector members; said transport member being provided with an additional perforated sheet metal cylindrical jacket arranged beneath the sheet metal strips.
A device of the type provided with sheet metal strips is known from DE 38 21 330 A1 and corresponding U.S. Pat. No. 4,912,945, the disclosure of which is incorporated herein by reference. It has the unsurpassed advantage that it is extremely permeable to air without thereby reducing the stability of the drum. Without having recourse to a welded construction, the sheet metal strips extending longitudinally across the drum are securely connected around the drum by means of the screw connection, preferably provided here, of the connector members extending in the peripheral direction. The disadvantageous microstructural changes in the metal during the manufacture of the otherwise necessary welded seams are avoided in this screwed structure.
Practice has shown that, particularly in the case of extreme drum lengths, and even in the case of the entailed small drum diameters, the air velocity in the center of the drum towards the fan becomes extremely high. In addition, the surface stresses on the drum which occur, depending on the density of the material to be treated, have an effect on the precision of rotation of the drum.